Plate type heat exchanger and method of manufacturing same



Oct. 20, 1953 j P. H'ODSON ET AL PLATE TYPE HEAT EXCHANGER AND METHOD OF MANUFACTURING SAME {2 sheets-s ag: 1

Filed Ju 1y 2 5 1948,

m m 5 w U l- 4 v. E M E amp PETER HODSON JNVENTORS P. HODSON ET AL 2,656,158 PLATE TYPE HEAT EXCHANGER AND METHOD OF MANUFACTURING SAME A 2 Sheets-;Sheet 2 Oct. 20, 1953 Filed July 23, 1948 \l I H II 42 Hill. 2 A N ERNEST/7 Lll/VDSTROM fl/VD PETE]? HODSO/V L Saga IN V EN TORS Patented Oct. 20, 1953 PLATE TYPE HEAT EXCHANGER AND METHOD OF MANUFACTURING SAME Peter Hodson, Wellsville, and Ernest A. Lundstrom, Valley Stream, N. Y., assignors to The Air Preheater Corporation, New York, N. Y.

Application July 23, 1948, Serial No. 40,336

10 Claims.

The present invention relates to heat exchange apparatus and particularly to a method of manufacturing heat exchanger components provided with extended surface in the form of pin-like fins or interrupted strip fins.

Various types of heat exchangers particularly those of the envelope type having passages formed by spaced plates for confining the fluids in heat exchange relationship are frequently provided with extended surface in the form of fins intended to increase the eificiency of heat transfer from a heated fluid on one side of the passage wall to a cooler fluid on the other side of the wall: The present invention contemplates the provision of finned components for use in heat exchangers either as a plate to form the walls of a fluid passageor as a member to be inserted in the passages of a regenerative exchanger to provide greater eificiency in heat exchange. Specifically, the invention involves methods of first forming perforations in a plate and then bending'it to form projections from its surface which will function as heat exchange fins.

The invention will be best understood upon consideration of the following detailed description of illustrative methods when read in conjunction with the accompanying drawings in which:

Figure 1 is a plan view of a perforated plate from which a heat exchange component is formed;

Figure 2 is a perspective view illustrating the manner in which the plate is bent to provide the heat exchange fins;

Figure 3 is a fragmentary perspective view illustrating the use of the heat exchange com ponents to form envelopes for a two fluid heat exchanger. 7

Figures 4 and 6 are plan views of sheets perforated for forming alternative arrangements of the fin surface;

Figure is a fragmentary sectional view through part of a heat exchanger embodying finned surface formed from the plate shown in Figure 4; and

Figure 'l is a sectional view through part of a heat exchange core of annular form embodying finned surface created from the plates illustrated in Figures 4 and 6.

In accordance with the invention the first step in the process of making finned heat exchange components is to punch or otherwise form in a plate Hi (Fig. 1) a plurality of perforations H disposed in parallel rows I 2' with theperforations alined from row to row or offset if it is deto prevent flow through the perforations made to the thickness.

2 sired to stagger the pin-fins. The plate is then creased on the lines AA extending along the axis of the rows l2 of openings and bent in what may be termed an upward direction along the lines 13-13 and (3-0 located at either side of each row I! at perforations Ii to raise the ligaments it that remain after punching the openings H above the surface of the unbent portions It of the plate. of each ligament i3 at either side of the crease line A.A are raised from the surface It of the plate and drawn together to create a series of projecting tabs orv fins 2t alined in a plurality of parallel rows extending transversely of the plate, the perforations H becoming notch-like spaces between the fins. The erection of the ligament portions iii to form the tab-like fins 20 results in the fins automatically alining with each other in rows extending transversely of the plate. This produces interrupted strip-fins extending in one direction onthe plate. By narrowing the width of the ligaments IS the tabs 2i] become more and more pin-like. The ligament'portions I5, it are then brazed together. When a fin is bonded to a plate that separates passages the heat to be transferred must traverse a double thickness of metal, i. e. the piece forming the fins and the wall itself. This increases the resistance to heat flow which is proportional Furthermore, it is difficult to assure that each fin is perfectly bonded to the wall separating the passages and lack of metal to metal contact in this region seriously affects heat flow. By forming the fins integral with the plate and using brazing or welding as a seal in the plate, one also assures perfect contact be tween the fins and plate without double thicknesses of plate being required.

When used in a heat exchanger a number of complete elements 2! each having a multiplicity of tab-like fins 26 may be stacked upon each other or with intervening plates 2| have channel fins 22 as illustrated in Figure 2 and then brazed together so that the portions M form walls of the fluid passage having the fins 2%! extending therefrom. Alternatively, complete elements 2! stacked together (with or without brazing) into a unitary mass may be inserted in the fluid passages of a regenerative heat exchanger, for example, to absorb and temporarily store heat from gases before imparting to air or other fluids.

The plate 3i; illustrated in Figure i-has rows of perforations 31! disposed in pairs separated by a portion 32 of the plate which becomes part Thus, the halves l5, l6

of the passage wall. In this alternative method the plate 36 is creased on the lines F-F lying between the two rows of a pair. Thus the bend line is at the base of the ligaments 34, 35 between the perforations in the various rows. The plate is then. bent inv an upward direction on the lines GG and'H-I -I;so that..; entire ligaments 34 between the perforations in the row 32 are brought into contact with entire ligaments between the perforations in the row 33.

surface of the plate when viewedizineside...elevation present the appearance ofaperforatedstrip as pears in the upper part.ofliigurefi-while-in end elevation each double thicKnessLfinAO-is.

spaced from the adjacent fins and connected thereto by portions 32 of the plate.

This form of finned plate is particularly adapts ed for use in a heat exchanger wherein the core iseof annular cross section as illustrated in Figure i7, since by' slanting' the bend lines "KQand' L with respect 110 the axes of the row 'of-"perforations as indicated in Figure '6 the plate portion- 32"between :the rows 34", 35 of '{perforations will in effect be progressively wider along the core radius with one side -42 of the finned strip tapered" to accommodate-the radial flow passages of? the annular core-whilethe-distal ends 42' of the pin-fins will lie in a common plane NN coinciding with the radius on the opposite wall of thepassa ge; Figr'? showsa-porti'on of a core of annular shape in which onefluid flows parallel to {the center'of the corein'the passages 4'3 while theiother' fluid fiowsrradiallfy in the passages 44. 'Thistype core is made'by alternatingplates 32 bent asshown in Fig. 4 for the passages-normal to the radius with plates 46 bent as shown in "Fig; '6 for the radial'- pa=ss ages. The-progressively longer fins 141 will: allow these latter passages to taper toward, acornmon center resultin'g i n a corehavinganannular shape.

What'we claim is;

1. Ijhe method o-f forming afinned heat transfer element of plate form for use in a heatexchanger which comprises; forming in' the surface of a plate" ofheat exchange -materia'l;a plurality ofspaced perforations alined in para'llel rows creasing the-plate alonglines parallel to one edge of saidplate fo-r;;ra i sing 'theligaments remaining between"perforations-from the surface of ,theplate; squeezing theraised ligament portions of the-plate into contact; and 'Welding or brazing the ligament portions together for forming unitary'fins and sealing off fluid flow through said perforations fromionezside' ofthe plate to the other.

2. The method of forming a finned heat transfer element of plate form for use ina heat exchanger which comprises; forming in the surface of a plate of heat exchange material a plurality of spaced perforations'alined in parallel rows; folding ,the ligaments remaining in the plate between perforations upwardly-along lines parallel to the axis of the rows and at either side thereof to; raise the ligaments from the surface of the plate; creasing the raised ligaments along lines corresponding to the axis of the 'rows of apertures and squeezing together theup-folded ligament portions to create tab-like fins of double thickness'projecting from the surface of the-plate; andwelding or brazing the'thickness of'the tabs to each otherto-form unitary-fins.

3; The-method of forming a finned heat transfer element of plate form-for use in aheat eX--' changerwhic-h comprises; forming in thesur The double thickness fins thus raised fromsthe face of a plate of heat exchange material a plurality of spaced perforations alined in parallel rows; creasing the ligaments remaining in the plate between perforations along lines corresponding to the axis of the rows of apertures and bending the plate upwardly along lines parallel to the axis pf'themows and at eithenside thereof to raise the ligaments from' the surface of the plate; squeezing together the up-folded ligament portions to create tab-like fins of double thickness-projecting from the surface of the plate; and-welding or brazing the thicknesses of the ,finto eachother to form unitary fins.

rlzfi'lfheimethod ofrforming a finned heat trans- 1 jenelemcntof'plate' form for use in a heat exchanger which comprises; forming in the surfaceiofi asplatelofiheat exchange material a plurality of spaced perforations alined in parallel rows; bending the platealong lines parallel to the rows of perforations to raise the ligaments between thelatter-from'thesurface of'the plate as spaced-fins; squeezing the raisedv ligament portions of -the'-plate into contact and Welding or brazingthemtogether.

5. The method of formingafinned heat transfer "element of-plateform for useina heat exchanger-which comprises; formingin the surfaceof-aplate of heat exchange material a plurality of spaced 'perforationsalined in parallel rows; creasing'the platealong dines extending between two contiguous 'rows of perforations and bending the plate'upwardly along fold lines at either side ofsaid pair of rows of perforations to'rai'se the ligaments remaining: between perforations-from the surface-of the plate; squeezing the creased ligaments in contact and bonding them toget'her to form fins projecting, from the pl'atesurface.

6'. Themethod of'formi'ng a finned heat transfer element ofjplate -form forusein aheat'exchanger'which comprises; forming inthe surface of a plate-of heat exchangema-teriala plurality ofspaced perforations alined" in parallel rows: bending the plate in an upward direction along parallel foldlines lying at either side of each contiguous pair ofrows of-perf'orations to raise theligaments between perforations from the surface of the plate; creasing the plate along lines parazllel' to" said fold lines to bring the ligaments--between the perforationsof one-row into contact with those between the locations of the contiguous row; and Welding or brazing the raised ligaments together for forming unitary fins projecting from the plate surface'.

'7. The =method' as recited in claim 5 wherein theplate-isbent along divergent fold lines.

8'. In aheat-exchanger; a wall member separating passages for two streams of fluid between,

which heat is to be exchanged consisting-of a plate-memberhaving a plurality of rows-of closely spaced narrow tab-like fins projecting from its surface, said. tab-like fins comprising doubled ligament portions of the plate located between perforations spaced inv rows; therein, abutting faces of said doubled ligament portions being bonded together so as-to prevent leakage .of fluid from one-side of saidplate wall to the other side thereof.

9. In a heat exchanger; a wall separating the passages for two streams of fluid between which hcatiis' to. be exchanged consisting of. a plate member: having ;aplurality of rows ofv closely spacedxnarrow tab-like .fi-ns projecting from its surface and made up of half-parts of narrow plate tligamentsnbetween perforations spaced, in

rows therein, said half parts of plate ligaments in an abutting relation and bonding material joining said ligament portions to form integral narrow fins thereof to prevent leakage from one side of said plate wall to the other side thereof.

10. A heat exchanger made up of a plurality of wall members formed as recited in claim 9 stacked upon each other so as to provide a core in which all of the walls separating passages for fluid flow are formed from plate members With fins integral therewith located in the passages.

PETER HODSON. ERNEST A. LUNDS'IROM.

Name Date Serve Sept. 14, 1886 Number Number 15 Number Name Date Gildersleeve Sept. 3, 1912 Stolp Dec. 24, 1912 Streichert Mar. 25, 1913 Hanmer Mar. 1, 1921 Steenstrup Mar. 17, 1931 Whitlock Sept. 19, 1933 Ridgway May 29 1934 Ramsaur Nov. 26, 1940 Bowers Aug. 4, 1942 Elder Oct. 2, 1945 Belaieff Oct. 21, 1947 FOREIGN PATENTS Country Date Great Britain of 1901 Great Britain Sept. 14, 1886 Great Britain Jan. 28, 1946 France of 1924 

